1. Field of the Invention
The present invention relates to a magnetic recording and reproducing device which records data on a magnetic recording medium, and reproduces the data, and, more particularly, to a technology for protecting a reproducing head.
2. Description of the Related Art
Recently, the magnetic recording and reproducing device such as a hard disk has been utilized as a recording medium used in an electronic equipment in many cases. In such a magnetic recording and reproducing device, a magneto resistive (MR) element is used for a head reproducing data which has been magnetically recorded. As a value of resistance in the MR element is changed by a change in a magnetic flux, a voltage between the both ends is measured under a state in which a predetermined bias current is passed through the element, and information recorded in the magnetic recording medium may be read in the form of the converted voltages.
It has been known that such an MR element has a low breakdown voltage, and is easily affected by noise such as static electricity (Patent Document 1). On the other hand, a giant magneto resistive (GMR) element, a tunneling magneto resistive (TMR) element, and the like, which may realize more integration, have been used as the capacity of the magnetic recording and reproducing device increases. However, the above elements have a further low breakdown voltage to present an important problem that a protection technology for the elements is required.
[Patent Document 1] Japanese Patent Application Laid-open No. 6-176558.
A magnetic recording and reproducing device provided with the above-described MR element has had the following problems.
FIG. 6 shows a configuration in the vicinity of a head in a commonly used magnetic recording and reproducing device. As shown in FIG. 6, a magnetic recording and reproducing device 100 is provided with a reproducing head 10, a recording head 12, and a magnetic head driving circuit 200 which supplies a bias current to the both heads. The magnetic head driving circuit 200 includes a reproducing head driving circuit 14 and a recording head driving circuit 16, wherein the circuits are integrated.
In many cases, there has been applied a configuration in which while the reproducing head 10 and the recording head 12 are provided in the vicinity of a hard disk as a magnetic recording medium, the magnetic head driving circuit 200 is provided at a position away from the heads, and four interconnections Rx, Ry, Wx, and Wy are routed therebetween. As these interconnections are routed over a distance of several centimeters under a state in which the interconnections are adjacent to each other, each of parasitic capacitances between the interconnections can not be neglected.
Here, when recording operation is operated in the magnetic recording and reproducing device 100, the recording head driving circuit 16 switches, at high speed, a write current passing through the recording head 12, and there are caused crosstalks of the above write current into the interconnections Rx and Ry on the side of the reproducing head 10 through each of the parasitic capacitances between the above-described interconnections. Thus, a voltage between the both ends of the reproducing head 10 is changed according to the switching of the write current during recording operation. Accordingly, there may be a great possibility that the life and the reliability of the reproducing head 10 are affected.
Here, there may be considered a method by which a constant current source, which supplies a constant current to the reproducing head 10, is grounded at recording operation, and potentials of the both ends of the reproducing head 10 is fixed in order to protect the reproducing head 10. However, the above method has had a problem that, when operation is shifted to the reproducing operation, it takes time to reset the constant current source and high-speed recording and reproducing are obstructed. Moreover, when a circuit is provided for high-speed resetting, the size of the circuit is increased.